The objective of this study is to gain information concerning the biochemistry of certain acrosomal enzymes, their seminal plasma inhibitors, capacitation, and sperm-ovum fusion in the human. Sperm hyaluronidase, "corona penetrating enzyme" and acrosin are known to have an important role in the fertilization process, and these enzymes will be isolated and characterized from human spermatozoa. Particular emphasis will be placed on their active site and kinetic properties, and the reaction with specific synthetic inhibitors. Their interaction with the naturally occurring antifertility agents: decapacitation factor and proteinase inhititors, will be studied. These inhbitors will be purified and characterized from human seminal plasma. They will be cleaved to low Mw peptides that retain their antifertility and inhititory activity; the peptides will be isolated, analyzed, and possibly synthesized. The location of these enzymes and seminal plasma inhibitors on human spermatozoa will be evlauated as well as their role in the capacitation process. The layers surrounding the ovum will be studied biochemically and their interactions with the acrosomal enzymes will be tested. The immunogenic properties of the acrosomal enzymes will be determined. The proposed studies will lead to a better understanding of the fertilization process in the human. Additionally they are of practical value since the inhibition of acrosomal enzymes prevents fertilization. Increased knowledge of these enzymes and their inhibitory agents may therefore lead to the development of new contraceptive agents. Further a more thorough understanding of the naturally occurring antifertility agents from human seminal plasma will give insight into the capacitation process and may lead to the preparation of active derivatives with high contraceptive ability that have few if any side-effects.